Currently, there exist a number of surgical anastomotic circular staplers. Generally, these staplers are used to perform an inverted connection of severed tissue with a circular ring of staples displayed around a circumference to connect the tissue. An inverted connection is one where serosa is joined to serosa. In some instances, to maximize the inside diameter of the lumen, a knife mechanism is used to cut the excess tissue within the circumference of the staple ring. The ring of staples is generally a number of small metallic surgical staples, usually between 20 and 40 staples, which form a ring roughly 2 cm to 4 cm in diameter. Naturally, with the inverted connection and with the circular rows of staples there will be some constriction of the tissue during and after healing. Ideally, the lumen diameter at the anastomotic site must be maintained as near as possible to that of the normal healthy bowel, prior to the procedure, to allow normal passage of semisolid materials.
With this type of anastomosis, to prevent infection and abscess, there must be a complete 360.degree. seal of tissue so that no gaps exist between the connected tissue. In addition, it is naturally desirable that when the tissue is connected, the interior volume of the lumen within which the tissue is cut be maintained so that resectioned vessel tissue is continually able to pass fluids while encountering only a minimum of constricting tissue.
In addition, with such circular anastomotic devices it is often desirable to make applier tools which are disposable. That is, disposable instruments are now well accepted by surgeons. Disposable surgical staplers and the like also help prevent the spreading of bacteria or germs. Naturally, the surgeon also desires an instrument which gives good-off-the-shelf reliability and allows a controlled one-handed operation. If necessary to meet the above criteria, it should be possible to construct this device applier to meet disposable needs.
It is also desirable to replace a standard staple line with two adaptively connectable couplers or fasteners. In this way, the need for bending of staples is removed, and yet closure and hemostasis are possible. Of course, by attempting to formulate a system in which a standard staple line is replaced, it would be desirable to formulate such a stapler so that the stapler itself can be pulled through the attached part of the tissue without the need for removing the anvil portion of the stapler. This results in a rapid and efficient method of removing the stapler.
In the desire for creating such a adaptively connectable mating coupler/fastener, it is naturally desirable that these fasteners are both positively aligned and latching, and that they are formulated so that the instrument creates closure with some constantly adjustable closure pressure. If the pressure required to attach the latching members together remains constant, it is much easier to close and latch the instrument with a smooth, efficient single stroke. Alternately, it may be desirable to rely on the constant closure pressure to attach the fastener through the tissue, and then, in a separate action, actually close the tissue with the instrument.
The inventions described in Ser. No. 642,696, entitled "Pull Through Anastomotic Intraluminal Stapler with Absorbable Fastener Means" and U.S. Pat. No. 5,250,058 entitled "Absorbable Anastomotic Fastener Means", assigned to a common assignee, and herein incorporated by reference, provide a mechanism arranged to anastomose two lumens with an absorbable fastener. The fastener is created from two washer-like pieces and is similar to that described above. One of the washer-like pieces has holes which are adaptable to receive latching prongs protruding from the other such washer-like piece. Fastening is accomplished through a singular linear motion in which the prongs pierce the tissue, then latch within the holes in the receiver. Finally, the tissue is cut by a substantially circular knife which also creates a final ring-like shape of the fastener within the tissue. The inner portion of each of the washer-like pieces is removed along with the cut tissue when the instrument is removed from the lumen.
With conventional circular staplers (both metallic and absorbable) it is necessary to perform the resectioning of vessels by first tying the vessel ends individually around a center section of the staple applier. This is necessary to assure that the entire circumference of the open tubular vessel is within the inverted junction. This procedure is commonly called a "purse-string" in that it resembles the tie around the open neck of a purse. It is a difficult and time consuming procedure to do in an open procedure and nearly impossible except for the most adept surgeons, to do laproscopically.